<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Object.prototype.hasOwnProperty</title>
</head>
<body>
        <ul>
        <li>今天</li>
        <li>明天</li>
        <li>后天</li>
        </ul>
        <script>
            var s = document.getElementsByTagName('li');
            var i;
            for( i in s){
//                    s.hasOwnProperty(i); true/false
                if (s.hasOwnProperty(i)){
                    console.log(s[i])
                }


            }

        </script>
</body>
</html>